General Session II
Genomic Tools in Cattle Selection
COLUMBIA, Mo. (June 30, 2010) — A compilation of genomics research indicates new tools are radically changing dairy breeding decisions and, in the future, may do the same for the beef industry.
Curt Van Tassell“Selection works in dairy. Trends in U.S. milk production show that in 2007 the U.S. produced 34% more milk with 48% fewer dairy cows than in 1960,” says Curt Van Tassell, a research geneticist at the Bovine Functional Genomics Laboratory and the Animal Improvement Programs Laboratory at USDA’s Agricultural Research Service facility in Beltsville, Md.
Traditional selection methods include collecting phenotypic data, estimating the genetic merit and selecting the superior animals. Now, Van Tassell says, genomics research is revealing how rapidly and more accurately technology will change how producers make selection decisions.
In 2006, Van Tassell and other researchers gathered genotypic date on 3,000-5,000 Holstein cows, 750-1,000 Jerseys and 250-400 Brown Swiss. Holstein data had built-in validation with a historic group of bulls and a prediction group of bulls. Van Tassell says they learned quickly they had significant reliability in the data, as accuracy more than doubled with genomic results. Accuracy improved from 40% to 70% reliability on young bulls.
“The problems we saw were that there was an upper limit on the accuracy of genetic prediction, even in Holsteins, and we questioned what to do with the smaller breeds. Marker effects were not consistent enough to justify across-breed genetic prediction,” he says.
Van Tassell says development of a bovine high-density (HD) SNP (single-nucleotide polymorphism) assay will help increase accuracy in genetic prediction. With help from Illumina, Pfizer and several research institutions, a bovine HD gene chip should be available next month. The promising chip was created to use across-breed information, enhance gene-mapping precision and more. A large number of the SNPs discovered will become publicly available.
“A low-density assay will be of value, too, especially in the third world, for parentage, traceability in the instance of diseases and to provide genetic prediction and a shortcut to pedigree data,” he says. “The technology is applicable to extensive management practices.”
Lastly, Van Tassell touched on genotype imputation, which will allow prediction of unknown and observed genotypes. Researchers are currently exploring pedigree haplotyping, where a pedigree could be used to reconstruct likely haplotypes and predict the dam from the progeny. It ultimately could also help increase the reliabilities of genomic technology.
Van Tassell spoke June 30 during the second general session of the 2010 Beef Improvement Federation (BIF) symposium. Themed "Gateway to Profit," the 42nd annual research symposium and annual meeting was hosted by BIF June 28-July 1 in Columbia, Mo.
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